JP2002221298A - Hydrogen storage apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the weight of a hydrogen storage apparatus. SOLUTION: The hydrogen storage apparatus 1 is provided with a hydrogen storage means 3 (MH tank aggregate) housing a hydrogen storage alloy, and a hydrogen tank 2 (high pressure one) for storing hydrogen in a gaseous state separately from the means 3, and is composed such that the pressure of the hydrogen tank 2 is higher than that of the means 3. The apparatus 1 is also provided with a pressure reduction means 6 (regulator for charging) for reducing, to a prescribed level, the pressure of hydrogen supplied from a hydrogen charging device for supplying hydrogen to the apparatus 1 and charging thereinto. Further, the hydrogen storage means 3 includes a plurality of tanks 31 (MH tanks) housing hydrogen storage alloy, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogen storage device for supplying hydrogen to a hydrogen utilizing device such as a fuel cell.

[0002]

2. Description of the Related Art In recent years, fuel cell electric vehicles (FCEVs) have attracted attention in terms of the environment, such as suppressing the emission of carbon dioxide that causes global warming. A fuel cell electric vehicle is equipped with a fuel cell (FC) that generates electricity by electrochemically reacting hydrogen (H ₂ ) and oxygen (O ₂ ) in the air, and runs the electricity generated by the fuel cell. The driving force is supplied to the motor.

[0003] As a device for supplying hydrogen to a hydrogen-using device such as a fuel cell, a hydrogen storage device using a pressure-resistant airtight container (hereinafter referred to as an "MH tank") containing a hydrogen-absorbing alloy has attracted attention. MH is Meta
l Hydride. This hydrogen storage alloy
It is an alloy that can absorb (occlude) a large amount of hydrogen (hydrogen gas) and extract (release) the absorbed hydrogen as needed. As a characteristic of the hydrogen storage alloy, the temperature rises due to heat generation when storing hydrogen, and the temperature decreases due to heat absorption when releasing hydrogen. As shown in FIG. 6, the hydrogen storage alloy has the following characteristics: as the temperature of the hydrogen storage alloy increases, the equilibrium hydrogen pressure also increases (high-temperature shift),
As the temperature decreases, the equilibrium hydrogen pressure also decreases (low temperature shift). That is, considering the storage time, when the temperature of the hydrogen storage alloy increases, the equilibrium hydrogen pressure increases, so that the amount of hydrogen that can be stored decreases. On the other hand, considering the time of release, when the temperature of the hydrogen storage alloy decreases, the equilibrium hydrogen pressure decreases, so that the released hydrogen cannot be sufficiently released. Therefore, in the hydrogen storage device, the MH tank is cooled when storing hydrogen to prevent a temperature rise, and when releasing hydrogen, the MH tank is heated to prevent a temperature drop.

[0004] On the other hand, when a heat source for heating the MH tank cannot be obtained, for example, at the time of starting the hydrogen utilizing device (at the time of cold start), the hydrogen cannot be sufficiently released from the MH tank. Therefore, the hydrogen storage device employs a configuration in which an auxiliary tank capable of releasing hydrogen at a low temperature is additionally provided. For example, Japanese Patent Application Laid-Open No. 5-106513 describes a hydrogen fuel supply device for a hydrogen engine having a configuration in which a normal hydrogen storage tank and a start-up hydrogen storage tank are provided. The hydrogen storage tank for starting the hydrogen fuel supply device contains a hydrogen storage alloy that releases hydrogen at a low temperature without being heated.
Also, since the internal pressure of the hydrogen storage tank at the time of start-up becomes high, in order to suppress increase in weight and to provide pressure resistance,
The hydrogen storage tank for startup is small. When the engine is started in the cold state, hydrogen is supplied from the starting hydrogen storage tank to start the hydrogen engine.

Japanese Patent Application Laid-Open No. Hei 7-101255 describes a hydrogen vehicle having a main fuel tank filled with a hydrogen storage alloy and a small-capacity auxiliary fuel tank.
In this hydrogen vehicle, hydrogen is supplied to the engine from the auxiliary fuel tank at the time of starting. In some cases, hydrogen is supplied to the sub fuel tank from the main fuel tank. In some cases, the auxiliary fuel tank is filled with a hydrogen storage alloy.

Japanese Patent Application Laid-Open No. 9-142803 discloses that a gas tank is connected to a gas outlet of a hydrogen storage alloy tank filled with a hydrogen storage alloy via a check valve,
A hydrogen gas supply device in which a hydrogen supply pipe for supplying hydrogen to an external device (fuel cell) is connected to a gas outlet of a gas tank is described. This hydrogen gas supply device has a configuration in which a gas tank is provided between the hydrogen storage alloy tank and the fuel cell, and utilizes that the pressure in the gas tank is sufficiently high (about 0.9 MPa) by a check valve. Thus, at the time of startup, hydrogen is supplied from the gas tank to the fuel cell. On the other hand, since the internal pressure of the hydrogen storage alloy tank increases when the temperature of the hot air discharged from the fuel cell body increases after the start-up, the check valve is used to supply hydrogen from the hydrogen storage alloy tank.

Japanese Patent Application Laid-Open No. 2000-12062 discloses a main hydrogen storage tank containing a high-temperature hydrogen storage alloy that releases hydrogen at a predetermined high temperature state, and a hydrogen storage tank at a lower temperature state than the predetermined high temperature state. A hydrogen gas supply device including a secondary hydrogen storage tank or the like containing a low-temperature hydrogen storage alloy that can be released is described. This hydrogen gas supply device supplies hydrogen to the external load (fuel cell) from the secondary hydrogen storage tank when the internal pressure of the main hydrogen storage tank is low, that is, at the time of startup.
After the startup, when the internal pressure of the main hydrogen storage tank increases, hydrogen is supplied from the main hydrogen storage tank to an external load.

[0008]

However, in the above-mentioned prior art, the problem of supplying hydrogen at the time of starting can be solved, but the problem of weight cannot be solved. That is, since the MH tank containing (filling) the hydrogen storage alloy is compact but heavy, there is a problem that, for example, when mounted on a fuel cell electric vehicle, fuel efficiency is deteriorated. In addition, there is a problem that handling is difficult if the weight is heavy. Therefore, it is necessary to reduce the weight. On the other hand, if the amount of hydrogen that can be stored for weight reduction is reduced, it is not preferable that the mileage of the fuel cell electric vehicle is shortened. In addition, heat generated when storing hydrogen in the MH tank reduces the filling rate (occluding rate) of hydrogen into the hydrogen storage device.

Accordingly, an object of the present invention is to provide a lightweight hydrogen storage device that solves the above-mentioned problems.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies, and have developed a hydrogen storage apparatus into a hybrid system combining a hydrogen storage means containing a hydrogen storage alloy and a hydrogen tank storing hydrogen in a gaseous state. In addition, the inventors have found that the above problems can be solved by appropriately setting the respective pressures, and have completed the present invention. That is, the hydrogen storage device of the present invention that has solved the above-mentioned problems (Claim 1)
Is a hydrogen storage device comprising a hydrogen storage means containing a hydrogen storage alloy, and a hydrogen tank for storing hydrogen in a gas state separately from the hydrogen storage means, wherein the pressure of the hydrogen tank is higher than the hydrogen storage means. Characterized by having a structure in which hydrogen is charged so as to be higher.

An MH tank according to an embodiment of the invention to be described later corresponds to a hydrogen storage means, and a hydrogen storage alloy is housed therein. On the other hand, a high-pressure hydrogen tank according to an embodiment of the invention described later corresponds to a hydrogen tank, and stores hydrogen at a high pressure. Among these, the hydrogen storage means has an optimum pressure (storage pressure) for storing hydrogen from the relationship between the equilibrium hydrogen pressure of the hydrogen storage alloy and the pressure resistance structure, and the amount of hydrogen that can be stored no matter how high the pressure is Does not increase to match the increased pressure. Conversely, the thickness of the material constituting the hydrogen storage means is required to ensure the pressure resistance, and the weight of the hydrogen storage means increases. On the other hand, the hydrogen tank
According to Charles' law, the higher the pressure, the more hydrogen can be stored. Therefore, in this configuration, hydrogen is stored such that the pressure of the hydrogen tank is higher than that of the hydrogen storage means. Further, when the hydrogen storage alloy stores hydrogen, a large amount of heat is generated. In this configuration, hydrogen is also stored in the hydrogen tank. Therefore, unlike storing hydrogen only with the hydrogen storage means, the load on the hydrogen storage means is reduced (the calorific value of the hydrogen storage alloy can be reduced). When filling the hydrogen tank with hydrogen,
Although heat is generated by adiabatic compression or the like, the calorific value is smaller than that of the hydrogen storage means containing the hydrogen storage alloy.

Next, the hydrogen storage device according to claim 2 is
The structure of claim 1 is characterized by comprising a pressure reducing means for reducing the pressure of hydrogen supplied from a hydrogen filling device for supplying and filling hydrogen to the hydrogen storage device to a predetermined pressure.

[0013] The hydrogen storage device supplies the stored hydrogen to a hydrogen utilization device such as a fuel cell to be empty.
Then, hydrogen is charged into the hydrogen storage device. In this configuration, the pressure of hydrogen supplied from the hydrogen filling device is reduced by a pressure reducing means (for example, a regulator, a throttle, a pressure reducing valve, etc.).
As a result, the pressure is reduced to a predetermined pressure. Of course, the pressure is reduced to a pressure that satisfies the condition that the pressure of the hydrogen tank is higher than that of the hydrogen storage means.

Further, the hydrogen storage device according to claim 3 is
In the configuration of claim 1 or 2, the hydrogen storage means is configured to include a plurality of hydrogen storage alloy tanks each storing a hydrogen storage alloy.

The hydrogen storage means containing the hydrogen storage alloy includes:
It is cooled when storing hydrogen and heated when releasing hydrogen. According to this configuration, the surface area of the hydrogen storage means can be increased, so that heating / cooling becomes easy.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

First, the present inventors grasped the relationship among the internal pressure, volume, and weight of the MH tank as the hydrogen storage means by simulation. The simulation conditions are as follows. (1) The MH tank has a cylindrical shape made of an aluminum alloy having a length of 800 mm. (2) Fill the MH tank with a predetermined BCC-based hydrogen storage alloy at a predetermined filling rate. (3) 100 g of hydrogen is stored (filled) in the MH tank. Under these conditions, depending on the internal pressure (storage pressure) of the MH tank,
A simulation was conducted on how the required volume and weight of the MH tank (including the weight of the hydrogen storage alloy) changed. Under this condition, when the hydrogen storage alloy cannot store a large amount of hydrogen, for example, when the pressure of the MH tank is low, a large amount of the hydrogen storage alloy is required to store 100 g of hydrogen in the MH tank. That is, the volume of the MH tank increases to accommodate a large amount of the hydrogen storage alloy (the diameter increases because the length is determined to be 800 mm). Of course, the weight of the hydrogen storage alloy stored in the MH tank and the weight of the material constituting the MH tank also increase.

Referring to FIG. 1, the relationship between the internal pressure, volume and weight of the MH tank obtained as a result of the simulation will be described. FIG. 1 is a diagram showing the relationship between the internal pressure, the volume, and the weight of the MH tank.
The horizontal axis indicates the internal pressure (storage pressure) of the MH tank. In FIG. 1, the solid line is a line indicating the relationship between the weight of the MH tank and the internal pressure, and the dotted line is a line indicating the relationship between the volume of the MH tank and the internal pressure.

As shown in FIG. 1, when the hydrogen pressure of the MH tank (hereinafter referred to as "the internal pressure of the MH tank") is low, both the weight and the volume of the MH tank increase. This is M
If the internal pressure of the H tank is low, the hydrogen storage amount of the hydrogen storage alloy is small (see FIG. 6), and a large amount of hydrogen storage alloy is required to store 100 g of hydrogen. In addition, the outer diameter of the MH tank is increased to accommodate a large amount of the hydrogen storage alloy (the number of materials is increased).

When the internal pressure of the MH tank is increased, both the weight and the volume of the MH tank rapidly decrease. this is,
Despite a slight increase in pressure in relation to the equilibrium hydrogen pressure (plateau pressure), the hydrogen storage amount of the hydrogen storage alloy rapidly increases (see FIG. 6), and the hydrogen required to store 100 g of hydrogen is obtained. This is because the amount of the occlusion alloy is significantly reduced. In addition, the outer diameter of the MH tank is significantly reduced because the amount of the hydrogen storage alloy is significantly reduced (a reduction in the amount of hydrogen storage alloy used is achieved).

When the internal pressure of the MH tank is further increased,
Reduction of the weight and volume of the MH tank by increasing the pressure reaches a limit. This is because, as shown in FIG. 6, when the hydrogen storage amount of the hydrogen storage alloy reaches saturation, the amount of the hydrogen storage alloy required to store the same 100 g of hydrogen is reduced even when the internal pressure of the MH tank is increased. This is because they cannot do anything.
By the way, when the internal pressure of the MH tank is increased, the amount of hydrogen stored by the hydrogen storage alloy increases, and hydrogen can be stored in a compressed state in voids other than the hydrogen storage alloy in the MH tank. The pressure is also increased, which is preferable because the amount of hydrogen that can be released at low temperatures increases.

If the internal pressure of the MH tank is further increased from this state, the weight and volume of the MH tank will increase. This is because while the hydrogen storage alloy cannot further store hydrogen, the increase in the internal pressure of the MH tank surely increases the thickness of the MH tank required to ensure the pressure resistance. Incidentally, when the thickness of the MH tank increases, it becomes difficult to transfer heat from the outside to the inside of the MH tank, and it becomes difficult to cool the hydrogen storage alloy in the MH tank at the time of occlusion. Then, the storage takes a long time or the amount of stored hydrogen decreases. On the other hand, at the time of release, it becomes difficult to heat the hydrogen storage alloy in the MH tank. Then, the required amount of hydrogen cannot be obtained when needed, and the response becomes poor. Note that there is a difference between the increase in the weight and the increase in the volume of the MH tank. This is because, when the internal pressure increases, the hydrogen existing in the gaps other than the hydrogen storage alloy in the MH tank is compressed, and the same 100 g of hydrogen is stored (stored).
This is because the volume of the MH tank (outer diameter of the MH tank) required to perform the operation is slightly reduced.

Next, the relationship between the internal pressure of the high-pressure hydrogen tank and the amount and weight of hydrogen stored will be described. Regarding the relationship between the internal pressure of the high-pressure hydrogen tank and the amount of stored hydrogen, the high-pressure hydrogen tank is a high-pressure container that stores gaseous hydrogen at a high pressure. The amount increases. In this point, it is different from the MH tank in which the hydrogen storage alloy is stored and the space portion is small.

Further, regarding the relationship between the internal pressure and the weight of the high-pressure hydrogen tank, it is necessary to increase the thickness of the high-pressure hydrogen tank when the internal pressure increases, and the weight of the high-pressure hydrogen tank increases as the internal pressure increases. In this respect, the tendency of the weight increase of the MH tank storing the hydrogen storage alloy is different from the tendency of the weight increase of the high-pressure hydrogen tank. Since the high-pressure hydrogen tank generates less heat than the MH tank and requires less heating / hydrogen cooling when discharging hydrogen than the MH tank, it is made of a lightweight resin (FRP) high-pressure tank. A hydrogen tank can be used. Therefore, even if hydrogen is stored at a high pressure, an increase in the weight of the high-pressure hydrogen tank can be reduced. Further, even when storing the same amount of hydrogen, the weight can be reduced as compared with the MH tank (the volume is larger than that of the MH tank) because the hydrogen storage alloy is not stored.

In the present invention, hydrogen is stored by a so-called hybrid system in which an MH tank and a high-pressure hydrogen tank are combined based on such knowledge.

Next, a hydrogen storage device according to an embodiment of the present invention will be described. FIG. 2 is a partially transparent side view of a fuel cell electric vehicle (hereinafter, referred to as “vehicle”) on which the hydrogen storage device of one embodiment is mounted. FIG. 3 is a block configuration diagram of the hydrogen storage device of one embodiment.

As shown in FIG. 2, the hydrogen storage device 1 according to this embodiment is mounted on a rear part of a vehicle. In the vehicle, an FC box is mounted under the floor of the passenger seat.
Inside this FC box is a fuel cell (hydrogen utilization device)
Is stored. Further, a traveling motor is mounted on a front part of the vehicle. Further, the fuel cell is connected to the hydrogen storage device 1 by a hydrogen supply pipe (not shown).

As shown in FIG. 3, the hydrogen storage device 1 includes a high-pressure hydrogen tank 2, an MH tank assembly 3, a hydrogen filling port 4,
It comprises a filter 5, a filling regulator 6, a first discharging regulator 7, a second discharging regulator 8, and a pipe connecting these. Note that reference numerals SV1 and SV
2 and SV3 are solenoid valves (cutoff valves). 3 includes a high-pressure hydrogen tank 2 and an MH tank assembly 3.
Are connected in parallel to the fuel cell (hydrogen utilization device).

The high-pressure hydrogen tank 2 is a resin tank made of fiber reinforced plastic (FRP), and has high pressure resistance and airtightness. Moreover, it is lightweight. The high-pressure hydrogen tank 2 is filled with hydrogen at a maximum pressure of, for example, 25 MPa. The high-pressure hydrogen tank 2 has a role of supplying hydrogen to the fuel cell when the discharge pressure of the MH tank assembly 3 is low because the temperature of the hydrogen storage alloy is low at the time of startup. Further, the high-pressure hydrogen tank 2 has a role of supplying hydrogen to the fuel cell even during normal times. That is, the relationship of the required (consumed) hydrogen amount of the fuel cell = the hydrogen release amount of the MH tank assembly 3 + the hydrogen release amount of the high-pressure hydrogen tank 2 is satisfied. In this respect, conventional techniques (JP-A-7-101255, JP-A-9-1428)
This is greatly different from simply supplying hydrogen only at the time of startup as in Japanese Patent Application Laid-Open No. 03-2003. Further, the high pressure hydrogen tank 2 greatly differs from the prior art in that hydrogen is stored at a pressure much higher than that of the MH tank assembly 3.

The MH tank assembly 3 is an assembly in which a plurality of MH tanks 31 of the same size are connected (the connection form may be serial or parallel). The MH tank 31 is a pressure-resistant airtight tank made of an aluminum alloy having higher heat resistance and higher thermal conductivity than resin. The hydrogen storage alloy is stored inside the MH tank 31. The MH tank 31 is capable of storing hydrogen at a maximum pressure of, for example, 3 to 5 MPa (lower than the pressure of the high-pressure hydrogen tank 2). Also, the MH tank 31
Are heated / cooled by heating / cooling means (not shown). Incidentally, the reason why the MH tank assembly 3 is an assembly of a plurality of MH tanks 31 is to perform heating / cooling of the hydrogen storage alloy with good responsiveness. The amount of hydrogen that can be stored as the MH tank assembly 3 is as follows:
The amount is set to be approximately the same as the amount of hydrogen that can be stored in the high-pressure hydrogen tank 2.

As the hydrogen storage alloy, for example, the following can be used. AB ₂ type alloy (Laves phase alloy); TiCr ₂ , (Z
r, Ti) (Ni, Mn, V, Fe) ₂ ··· AB ₅ type alloy; LaNi ₅ , MmNi ₅ ··· BCC-based alloy; Ti-V-Cr, Ti-V-Mn ··· Other; Mg-based alloy Mm in MmNi ₅ is an abbreviation for misch metal.

The hydrogen filling port 4 is used when a vehicle stops at a hydrogen station such as a gas station and fills with hydrogen. The hydrogen filling port 4 also serves as a check valve, so that hydrogen charged from a hydrogen filling device (not shown) does not flow backward.

The filter 5 is a filter for removing impurities, such as oxygen and moisture, which poison the dust and the hydrogen storage alloy in the hydrogen supplied from the hydrogen filling device.

The filling regulator 6 is a pressure reducing valve (pressure reducing means) for reducing the pressure of hydrogen supplied from the hydrogen filling device to the MH tank 31 to a predetermined pressure. The first discharge regulator 7 is a pressure reducing valve that reduces the pressure of hydrogen supplied from the high-pressure hydrogen tank 2 to the fuel cell to a predetermined pressure. The second discharge regulator 8 controls the pressure of hydrogen supplied from the MH tank assembly 3 to the hydrogen utilization device,
This is a pressure reducing valve that reduces the pressure to a predetermined pressure. Each of the regulators 6, 7, 8 has a role of a check valve.

The solenoid valve SV1 on the upstream side of the high-pressure hydrogen tank 2 normally supplies hydrogen of the high-pressure hydrogen tank 2 stored at a high pressure to the MH via the charging regulator 6.
It is not supplied to the tank assembly 3. Further, when the filling of the high-pressure hydrogen tank 2 is completed, a high hydrogen pressure is further supplied from the hydrogen filling device to prevent the high-pressure hydrogen tank 2 from being overfilled with hydrogen. Incidentally, even if the same amount of hydrogen is charged, the high-pressure hydrogen tank 2 can be charged with hydrogen in a shorter time than the MH tank assembly 3. The solenoid valve SV2 on the downstream side of the high-pressure hydrogen tank 2 prevents hydrogen from being supplied from the high-pressure hydrogen tank 2 to the fuel cell when not intended.
Also, the solenoid valve SV3 on the downstream side of the MH tank assembly 3
Similarly to the solenoid valve SV2, hydrogen is prevented from being supplied from the MH tank assembly 3 to the fuel cell when not intended. The solenoid valves SV1, SV2, SV3 are:
It is controlled by a control device (not shown).

The internal pressure of the high-pressure hydrogen tank 2 is measured by a pressure sensor (not shown). Further, the hydrogen storage amount (hydrogen storage amount) of the MH tank assembly 3
Is also measured by a pressure sensor (not shown). Each measurement value is transmitted to the control device, and the control device performs high-pressure hydrogen tank 2 and MH based on the measurement value.
A warning display of the remaining amount of hydrogen in the tank assembly 3 is performed. Incidentally, the temperature of the MH tank 31 is controlled to be a predetermined temperature in order to correctly know the remaining amount of the MH tank assembly 3 by the pressure.

Next, the operation of the above-described hydrogen storage device 1 will be described. 4 is an operation flowchart when the hydrogen storage device supplies hydrogen to the fuel cell. FIG. 4A shows a control program, FIG. 4B shows an MH tank assembly operation routine, and FIG. 4C shows a high-pressure hydrogen tank operation routine. Show.

The filling of the hydrogen storage device 1 with hydrogen is performed as follows (see FIG. 3). When the remaining amount of hydrogen in the high-pressure hydrogen tank 2 and the MH tank assembly 3 decreases, the driver stops at the hydrogen station and fills the vehicle (hydrogen storage device 1) with hydrogen. The remaining amount of hydrogen is determined by the control device based on the measurement value of the pressure sensor and notified to the driver (warning display).

For filling hydrogen, a hydrogen supply port of a hydrogen filling device (not shown) installed in a hydrogen station is connected to a hydrogen filling port 4 of the hydrogen storage device 1, and hydrogen is charged from the hydrogen filling device at a high pressure (for example, 35 MPa). It is started by supplying hydrogen to the device 1.

The hydrogen branches after flowing through the hydrogen filling port 4 and the filter 5, and one of the flows is supplied to the high-pressure hydrogen tank 2 through the open solenoid valve SV 1. The other branched flow flows through the charging regulator 6 and is supplied to the MH tank assembly 3. At this time, the solenoid valves SV2 and SV
Reference numeral 3 denotes a closed state, so that hydrogen is not supplied from the high-pressure hydrogen tank 2 and the MH tank assembly 3 to the fuel cell. The filling regulator 6 reduces the pressure of the high hydrogen supplied from the hydrogen filling device to, for example, 5 MPa. This filling regulator 6 allows each MH tank 3
Since an appropriate hydrogen pressure is applied to 1, the thickness of the MH tank 31 can be reduced to reduce the weight (and the size). Further, by reducing the thickness, heat transfer between the inside and the outside of the MH tank 31 can be improved.

When the filling of hydrogen is completed, the solenoid valve SV1 is closed, and the connection between the hydrogen filling port 4 and the hydrogen supply port is released. Since the hydrogen filling port 4 has a check valve function, when the hydrogen supply port is removed from the hydrogen filling port 4, hydrogen does not leak.

The hydrogen stored by the hydrogen storage device 1 is supplied to the fuel cell as follows (see FIGS. 3 and 4). First, a control program is executed by the control device (see FIG. 4A). In step S11 of the control program, “Internal pressure of MH tank assembly 3 ≧ 0.3
MPa (gauge pressure) "is determined. 0.3MPa
At a certain temperature (for example, 40 ° C.)
When the discharge pressure of the tank assembly 3 becomes lower than this value, M
This is a pressure at which it can be determined that the remaining amount of hydrogen stored in the H tank assembly 3 is almost exhausted, and varies depending on the type of the hydrogen storage alloy and the managed temperature. This pressure is a lower limit pressure required for stable operation of the fuel cell system (this pressure varies depending on the specifications of the fuel cell system).

If the internal pressure (40 ° C.) of the MH tank assembly 3 is equal to or higher than 0.3 MPa (YES), the flow shifts to an MH tank assembly operation routine to supply hydrogen from the MH tank assembly 3 to the fuel cell. (S12). On the other hand, when the internal pressure of the MH tank assembly 3 is less than 0.3 MPa (NO, empty), the process shifts to a high-pressure hydrogen tank operation routine to supply hydrogen from the high-pressure hydrogen tank 2 to the fuel cell (S
13). That is, when there is a remaining amount of hydrogen (residual pressure) in the MH tank assembly 3, hydrogen is supplied to the fuel cell preferentially from the MH tank assembly 3. By doing so, the MH tank assembly 3 for which it is difficult to detect the remaining amount can be emptied preferentially, so that the hydrogen capacity of the entire hydrogen storage device 1 can be easily detected.

MH tank assembly operation routine (FIG. 4)
(See (b))), the solenoid valve SV2 is closed and closed.
The solenoid valve SV3 is opened to open (S21). Thereby, hydrogen is supplied from the MH tank assembly 3 to the fuel cell via the solenoid valve SV3 and the second discharge regulator 8.

Next, it is determined whether or not “the internal pressure of the MH tank assembly 3 (hydrogen release pressure) ≧ 0.3 MPa (gauge pressure)” (S22). The meaning of the pressure of 0.3 MPa is as described above. When the internal pressure of the MH tank assembly 3 is 0.3 MPa or more (YES), the process is continued as it is, and the pressure of the MH tank assembly 3 is monitored. That is, the determination in step S22 is continued. This is because hydrogen to be supplied to the fuel cell still remains in the MH tank assembly 3. On the other hand, when the internal pressure of the MH tank assembly 3 is less than 0.3 MPa (NO), an MH tank assembly remaining amount warning display is performed (S23). This is for notifying the driver that there is no remaining hydrogen in the MH tank assembly 3. Then, return to the control program (RETURN).

Returning to the control program, in step S11, it is determined whether or not "the internal pressure (hydrogen release pressure) of the MH tank assembly 3 ≥ 0.3 MPa (gauge pressure)". Internal pressure of 3 is 0.3MP
If it is less than a (NO), the process proceeds to a high-pressure hydrogen tank operation routine (S13).

In the high-pressure hydrogen tank operation routine, the solenoid valve SV2 is opened and opened, and the solenoid valve SV3 is closed and closed (S31). Thereby, hydrogen is supplied from the high-pressure hydrogen tank 2 to the fuel cell via the solenoid valve SV2 and the first discharge regulator 7.

Next, it is determined whether or not “the internal pressure of the high-pressure hydrogen tank (hydrogen release pressure) ≧ 0.3 MPa (gauge pressure)” (S32). When the internal pressure of the high-pressure hydrogen tank 2 becomes lower than this value, the pressure of 0.3 MPa
Is the pressure at which it can be determined that the remaining amount of hydrogen stored in the tank has almost run out. Note that the change in pressure with temperature is M
The number is smaller than that of the H tank aggregate 3. If the internal pressure of the high-pressure hydrogen tank 2 is 0.3 MPa or more (YES), the process is continued as it is, and the pressure of the high-pressure hydrogen tank 2 is monitored.
That is, the determination in step S32 is continued. This is because hydrogen to be supplied to the fuel cell still remains in the high-pressure hydrogen tank 2. On the other hand, the internal pressure of the high-pressure hydrogen tank 2 is 0.3 M
If it is less than Pa (NO), a high-pressure hydrogen tank remaining amount warning display is performed (S33). This is for notifying the driver that there is no remaining hydrogen in the high-pressure hydrogen tank 2. Then, return to the control program (RETURN). Thereby, the hydrogen stored in the high-pressure hydrogen tank 2 and the MH tank assembly 3 is consumed.

The present invention is not limited to the above-described embodiment, but can be widely modified. For example, as in a modified hydrogen storage device 1A shown in FIG.
The line for filling the high-pressure hydrogen tank 2 with hydrogen and the line for filling the MH tank assembly 3 with hydrogen may be independent. This hydrogen storage device 1A corresponds to, for example, a case where a hydrogen filling device of a hydrogen station is provided with both a high-pressure line for filling a high-pressure hydrogen tank and a medium-pressure line for filling an MH tank assembly. In this case, the size and the like of the hydrogen filling port 4 may be different between the high-pressure line and the medium-pressure line from the viewpoint of preventing connection errors.

Alternatively, the solenoid valve SV1 shown in FIG. 3 may be changed to a check valve so that hydrogen is not supplied from the high-pressure hydrogen tank 2 to the MH tank assembly 3 at normal times. Also,
The solenoid valve SV1 may be used in combination with a regulator such as the charging regulator 6. Further, hydrogen may be simultaneously released from both the high-pressure hydrogen tank 2 and the MH tank assembly 3 and supplied to the fuel cell. Also, in FIG.
Although the high-pressure hydrogen tank 2 and the MH tank assembly 3 are connected in parallel to the fuel cell, the high-pressure hydrogen tank 2 and the MH tank assembly 3 may be connected in series to the fuel cell. . In this case, the high hydrogen pressure in the high-pressure hydrogen tank 2 and the high hydrogen pressure from the hydrogen filling device are not applied to the MH tank assembly 3.
With this configuration, it does not matter whether the high-pressure hydrogen tank 2 and the MH tank assembly 3 are connected in series or in parallel. Further, the present invention has been described by taking a fuel cell electric vehicle as an example, but the present invention can also be applied to a hydrogen vehicle equipped with a hydrogen engine using hydrogen as fuel. In addition, the present invention can be applied to a stationary hydrogen utilization device.

[0051]

According to the hydrogen storage device of the first aspect of the present invention described above, hydrogen is filled by combining a hydrogen storage means storing a hydrogen storage alloy and a hydrogen tank storing hydrogen in a gaseous state. Therefore, the weight of the hydrogen storage device can be reduced as compared with a case where the same amount of hydrogen is filled only by the hydrogen storage means. Further, the hydrogen storage device can be made more compact than when the same amount of hydrogen is stored only in the hydrogen tank. Further, by filling the hydrogen so that the pressure of the hydrogen tank is higher than that of the hydrogen storage means, the thickness of the hydrogen storage means can be reduced. That is, the weight of the hydrogen storage device can be reduced. Moreover,
Heating / cooling is facilitated by reducing the thickness of the hydrogen storage means, and hydrogen is easily extracted from the hydrogen storage means.
And it becomes easy to fill. Also, at the time of low-temperature start-up when the pressure of the hydrogen storage means is low, hydrogen can be supplied from the hydrogen tank. Further, the calorific value of the hydrogen storage means can be reduced as compared with the case where only the hydrogen storage means is filled with hydrogen. Filling (occluding) when the calorific value is reduced
The time can be shortened and the thermal load on the material constituting the hydrogen storage means can be reduced. Further, according to the hydrogen storage device of the second aspect, the pressure of hydrogen can be reliably reduced to a predetermined pressure and hydrogen can be charged.
Therefore, hydrogen can be reliably charged into the hydrogen storage device. According to the hydrogen storage device of the third aspect, since the hydrogen storage means is configured to include the plurality of hydrogen storage alloy tanks, heating / cooling is facilitated. Therefore, hydrogen can be taken out with high responsiveness and hydrogen can be stored (filled) quickly.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship among an internal pressure, a volume, and a weight of an MH tank.

FIG. 2 is a partially transparent side view of a vehicle (fuel cell electric vehicle) on which the hydrogen storage device of one embodiment according to the present invention is mounted.

FIG. 3 is a block diagram of a hydrogen storage device according to an embodiment of the present invention.

4 is an operation flowchart when the hydrogen storage device of FIG. 3 supplies hydrogen to the fuel cell, where (a) is a control program, (b) is an MH tank assembly operation routine, and (c) is a high-pressure hydrogen tank 3 shows an operation routine.

FIG. 5 is a block diagram of a hydrogen storage device according to a modification.

FIG. 6 shows P (pressure) -C indicating characteristics of a hydrogen storage alloy.
FIG. 3 is a (composition) -T (temperature) diagram.

[Explanation of symbols]

 1, 1A ... hydrogen storage device 2 ... high-pressure hydrogen tank (hydrogen tank) 3 ... MH tank assembly (hydrogen storage means) 31 ... MH tank (hydrogen storage alloy tank) 6 ... filling regulator (decompression means)

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshio Naoya 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3E072 AA10 EA10 5H027 AA02 BA13 BA14 DD00

Claims (3)

[Claims] 1. A hydrogen storage device comprising: a hydrogen storage means containing a hydrogen storage alloy; and a hydrogen tank for storing hydrogen in a gas state separately from the hydrogen storage means, wherein A hydrogen storage device having a configuration in which hydrogen is charged so that the pressure of a tank is increased. 2. The hydrogen storage device according to claim 1, further comprising a pressure reducing unit configured to reduce the pressure of hydrogen supplied from a hydrogen filling device that supplies and fills the hydrogen storage device with hydrogen to a predetermined pressure. Storage device. 3. The hydrogen storage device according to claim 1, wherein the hydrogen storage means includes a plurality of hydrogen storage alloy tanks each storing a hydrogen storage alloy.